Unique one-piece closed-cell EPDM sponge rubber gasket for most RV roof-mounted A/C and heat pump units. No seams, no leaks. Fits Dometic, Airxcel, Advent, Atwood, and Coleman. Includes gasket, leveling blocks, divider strip, and instructions. Higher UV, ozone, and weather resistance than original OEM gaskets. Hand crafted and made in USA.
The Steele Rubber Products 70-3905-207 is a unique, high-quality one-piece EPDM sponge rubber replacement gasket designed to fit most RV roof-mounted air conditioner and heat pump units, including those made by Dometic, Airxcel, Advent, Atwood, and Coleman. Unlike the original multi-strip gaskets installed by RV manufacturers at the factory — which are glued together from individual pieces — the Steele Rubber gasket is a single continuous piece with no seams, no joints, and no gaps for water to penetrate. The result is a proven no-leak installation that addresses the most common cause of roof leaks on RV A/C units.
Manufactured from high-quality closed-cell EPDM sponge rubber, this gasket delivers higher UV resistance, ozone resistance, and overall weather durability than what is originally supplied on most units. The closed-cell construction means the rubber does not absorb water or moisture, maintaining its compression and sealing effectiveness over time. Installation is straightforward thanks to the pressure-sensitive adhesive backing that holds the gasket in place during installation. The complete kit includes the one-piece gasket, two leveling blocks, a 14" divider strip (usable as a plenum divider or cut into additional leveling blocks), and a printed instruction sheet covering the full installation process.
Single continuous gasket with no seams, joints, or glued edges — eliminates the gaps that allow water to penetrate multi-strip factory gaskets
Closed-cell construction does not absorb water or moisture, maintaining compression and sealing effectiveness for the long term
Higher UV, ozone, and weather-resistant durability than original OEM gaskets — engineered to outperform and outlast factory materials
Includes gasket, leveling blocks, divider strip, and instructions — everything needed for a full replacement in one package
This gasket kit is designed to fit most RV roof-mounted air conditioner and heat pump units from the following manufacturers: Dometic — Roof-mounted A/C and heat pump units Airxcel — Roof-mounted A/C and heat pump units (including Mach series) Advent Air — Roof-mounted A/C units Atwood — Roof-mounted A/C units Coleman — Roof-mounted A/C and heat pump units Note on Coleman units: Some Coleman air conditioner gaskets have a wider outside diameter than the standard 17" x 17" outer dimension. In these cases, adjust the new gasket to fit properly by trimming or repositioning as needed. Always verify the gasket opening dimensions (14" x 14" inner, 17" x 17" outer) match your unit's roof opening before installing. Compatibility is not guaranteed on all model years and configurations.
Always disconnect all power to the A/C unit before beginning any work on the rooftop assembly or ceiling opening. • Work with a helper — having a second person on the roof or inside the RV significantly simplifies gasket installation and ensures the A/C unit is safely supported during removal and reinstallation • Inspect the roof deck around the A/C opening for any soft spots, water damage, or delamination before installing the new gasket — address any structural issues before proceeding • Remove all old gasket material and adhesive residue from the roof surface before applying the new gasket; applying over old adhesive will compromise the bond and sealing effectiveness • Do not work on the roof during high winds, rain, or when the roof surface is wet
Before You Begin: • Disconnect all power to the A/C unit • Have a helper available for roof work • Inspect the roof deck for water damage before proceeding Installation Steps: 1. Remove the A/C Unit: Unbolt and carefully lift the roof-mounted A/C unit off the roof deck 2. Remove Old Gasket: Peel away all old gasket material and adhesive residue from the roof surface around the opening 3. Clean the Surface: Wipe the roof deck surface clean and allow it to dry completely 4. Position the Gasket: Center the new one-piece gasket over the roof opening, aligning the 14" x 14" inner cutout with the A/C aperture 5. Peel and Press: Remove the adhesive backing and press the gasket firmly onto the roof deck surface 6. Install Leveling Blocks: Position the two included leveling blocks under the A/C unit corners to ensure the unit sits level 7. Use Divider Strip if Needed: Install the 14" divider strip in the plenum channel if your unit requires intake-to-return separation; otherwise cut it for additional leveling material 8. Reinstall A/C Unit: Lower the unit onto the gasket and secure with the mounting bolts — do not overtighten 9. Restore Power and Test: Reconnect power and test the unit for proper operation and verify no air or water leaks around the gasket perimeter
In The Kit: • One (1) one-piece EPDM sponge rubber A/C gasket (17" x 17" outer; 14" x 14" inner opening) • Two (2) leveling blocks (1-1/2" x 1" x 7") • One (1) divider/multi-use strip (1-1/2" x 1" x 14") • Printed installation instruction sheet • Pressure-sensitive adhesive pre-applied to gasket Sold Separately (If Needed): • Angled Plenum Divider 70-4284-207 — for units requiring a dedicated angled intake-to-return divider in addition to the straight strip
The included 14" strip serves two different purposes depending on your A/C unit type: Option A — As a Plenum Divider: If your A/C unit has a divided plenum (separate intake and return chambers), install the 14" strip in the ceiling plenum channel to separate the two airflow sides. This is required on most units with a divided plenum to maintain proper cooling performance. Option B — As Additional Leveling Blocks: If your unit does not require a plenum divider, the 14" strip can be cut into additional leveling block segments of any length needed to properly level the A/C unit on the roof deck. This allows full customization of the leveling arrangement. Note: If your unit requires an angled plenum divider (rather than a straight one), the separate Steele Rubber Angled Plenum Divider 70-4284-207 is available and is specifically designed for units needing an angled intake-to-return divider piece.
The one-piece design of the Steele Rubber gasket directly addresses the root cause of the most common RV A/C leak: the degradation and separation of the multi-strip factory gasket over time. By eliminating all seams from the perimeter seal, this replacement gasket provides reliable, long-term weatherproofing that the original installation method cannot match.